scholarly journals Brans - Dicke Cosmology with Causal Viscous Fluid

1996 ◽  
Vol 49 (5) ◽  
pp. 899 ◽  
Author(s):  
N Banerjee ◽  
A Beesham
Keyword(s):  
Scalar Field ◽  
Cosmological Model ◽  
Viscous Fluid ◽  
Exact Solutions ◽  
Power Function ◽  
Causal Theory ◽  
Scale Factor ◽  
Scalar Tensor Theory ◽  
Equilibrium Thermodynamics ◽  
Tensor Theory

Exact solutions for the spatially flat (k = 0) Robertson–Walker cosmological model in Brans–Dicke scalar tensor theory have been obtained in the presence of a causal viscous fluid. It is found that if the scale factor is a power function of the scalar field, then solutions can be obtained in the full causal theory but not in the truncated theory of non-equilibrium thermodynamics.

Isotropic Cosmological Model in Generalized Scalar Tensor Theory with Bulk Viscosity

1997 ◽  
Vol 06 (01) ◽  
pp. 119-124 ◽  
Author(s):  
N. Banerjee ◽  
Aroonkumar Beesham
Keyword(s):  
Scalar Field ◽  
Cosmological Model ◽  
Viscous Fluid ◽  
Bulk Viscosity ◽  
Conformal Transformation ◽  
Scalar Tensor Theory ◽  
Bulk Viscous Fluid ◽  
Tensor Theory ◽  
Bulk Viscous ◽  
Isotropic Cosmological Model

In this paper both exponential and power law solutions for the flat Robertson–Walker cosmological model have been derived in a generalized Brans–Dicke theory, where the parameter ω is a function of the scalar field, along with a bulk viscous fluid. The solutions are obtained in Dicke's revised units and these are also given in the original atomic units via the conformal transformation prescribed by Dicke.

COSMOLOGICAL MODELS IN GENERALIZED SCALAR–TENSOR THEORY WITH CAUSAL VISCOUS FLUID

1998 ◽  
Vol 07 (06) ◽  
pp. 849-856
Author(s):  
G. P. SINGH ◽  
S. G. GHOSH ◽  
AROONKUMAR BEESHAM
Keyword(s):  
Scalar Field ◽  
Viscous Fluid ◽  
Nonequilibrium Thermodynamics ◽  
Coupling Parameter ◽  
Scalar Tensor Theory ◽  
Bulk Viscous Fluid ◽  
Tensor Theory ◽  
Bulk Viscous ◽  
Friedmann Robertson Walker ◽  
Causal Thermodynamics

We consider generalized Brans–Dicke theory in which the coupling parameter is not constant but a function of the scalar field. Friedmann–Robertson–Walker models with bulk viscous fluid source described by full (i.e., nontruncated) causal nonequilibrium thermodynamics are analyzed. Exact solutions for the flat case have been obtained. Our results are compared with those in the usual Brans–Dicke theory with causal thermodynamics.

GENERALIZED SCALAR–TENSOR THEORY FOR BIANCHI SPACETIME MODELS

2004 ◽  
Vol 19 (09) ◽  
pp. 703-711
Author(s):  
NARAYAN CHANDRA CHAKRABORTY ◽  
SUBENOY CHAKRABORTY
Keyword(s):  
Scalar Field ◽  
Viscous Fluid ◽  
Einstein Equations ◽  
Physical Parameters ◽  
Scalar Tensor Theory ◽  
Coupling Constant ◽  
Bulk Viscous Fluid ◽  
Tensor Theory ◽  
Bulk Viscous ◽  
Variable Coupling

This work deals with Bianchi cosmological models where geometry is coupled to a scalar field with variable coupling constant (depending on the scalar field). Considering a bulk viscous fluid, the possibility of exponential or power law form of solutions have been examined. The modified Einstein equations have been solved with some reasonable assumptions among the physical parameters and solutions have been discussed.

scholarly journals EXACT SOLUTIONS FOR COSMOLOGICAL MODELS WITH A SCALAR FIELD

2002 ◽  
Vol 17 (03) ◽  
pp. 375-381 ◽  
Author(s):  
H. MOTAVALI ◽  
M. GOLSHANI
Keyword(s):  
Scalar Field ◽  
Exact Solutions ◽  
Cosmological Models ◽  
Coupling Function ◽  
Noether Symmetry ◽  
Scalar Tensor Theory ◽  
Frw Cosmology ◽  
Field Equations ◽  
Tensor Theory ◽  
Cosmological Solutions

We consider the existence of a Noether symmetry in the scalar–tensor theory of gravity in flat Friedman–Robertson–Walker (FRW) cosmology. The forms of coupling function ω(ϕ) and generic potential V(ϕ) are obtained by requiring the existence of a Noether symmetry for such theory. We derive exact cosmological solutions of the field equations from a point-like Lagrangian.

scholarly journals QUALITATIVE ANALYSIS OF A SCALAR–TENSOR THEORY WITH EXPONENTIAL POTENTIAL

2001 ◽  
Vol 16 (28) ◽  
pp. 4527-4541 ◽  
Author(s):  
A. B. BATISTA ◽  
J. C. FABRIS ◽  
S. V. B. GONÇALVES ◽  
J. TOSSA
Keyword(s):  
Phase Diagram ◽  
Scalar Field ◽  
Cosmological Model ◽  
Qualitative Analysis ◽  
Tensor Model ◽  
Scalar Tensor Theory ◽  
Exponential Potential ◽  
Ordinary Matter ◽  
Tensor Theory

A qualitative analysis of a scalar–tensor cosmological model, with an exponential potential for the scalar field, is performed. The phase diagram for the flat case is constructed. It is shown that solutions with an initial and final inflationary behavior appear. We discuss the possible existence of realistic scenarios and we generalize the results, adding ordinary matter to the scalar–tensor model.

GALACTIC AND ASTROPHYSICAL SIZES FROM SCALAR-TENSOR THEORY OF GRAVITY

2004 ◽  
Vol 13 (02) ◽  
pp. 359-371 ◽  
Author(s):  
GIUSEPPE BASINI ◽  
MARCO RICCI ◽  
FULVIO BONGIORNO ◽  
SALVATORE CAPOZZIELLO
Keyword(s):  
Scalar Field ◽  
Spiral Galaxies ◽  
Weak Field ◽  
Newtonian Potential ◽  
Scalar Tensor Theory ◽  
Field Limit ◽  
Weak Field Limit ◽  
Tensor Theory ◽  
Flat Rotation Curves ◽  
Theory Of Gravity

We investigate the weak-field limit of scalar-tensor theory of gravity and show that results are directly depending on the coupling and self-interaction potential of the scalar field. In particular, corrections are derived for the Newtonian potential. We discuss astrophysical applications of the results, in particular the flat rotation curves of spiral galaxies.

Brans–Dicke type teleparallel scalar–tensor theory

2017 ◽  
Vol 32 (34) ◽  
pp. 1750183 ◽  
Author(s):  
Mustafa Salti ◽  
Oktay Aydogdu ◽  
Hilmi Yanar ◽  
Figen Binbay
Keyword(s):  
General Relativity ◽  
Dark Energy ◽  
Scalar Field ◽  
Noether Symmetry ◽  
Scalar Tensor Theory ◽  
Minimal Coupling ◽  
Energy Effect ◽  
New Model ◽  
Symmetry Approach ◽  
Tensor Theory

The teleparallel alternative of general relativity which is based on torsion instead of curvature is considered as the gravitational sector to explore the dark universe. Inspired from the well-known Brans–Dicke gravity, here, we introduce a new proposal for the galactic dark energy effect. The new model includes a scalar field with self-interacting potential and a non-minimal coupling between the gravity and scalar field. Additionally, we analyze the idea via the Noether symmetry approach and thermodynamics.

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